A method of retrieving aerosol size distribution from the measured extinction of solar radiation at wavelengths 0.45 &mgr;m and 1.0 &mgr;m has recently been proposed. This method is utilized to obtain latitudinal and altitudinal variations of size distributions of stratospheric aerosols from the SAGE data for March 1979. Small particles are found in the lower stratosphere of the tropical region, and large particles are found at higher altitudes and latitudes in both hemispheres. Results of this study are consistent with the suggestion that the upper troposphere in tropical regions is a source of condensation nuclei in the stratosphere, and they become mature a they move to higher altitudes and latitudes.